Window port is the coordinate area specially selected for the display. Region Created according to World Coordinates. It is a region selected to form the real world. It is a graphically control thing and composed of visual areas along with some of its program-controlled with help of window decoration. A window port can be defined with the help of a GWINDOW statement.

The viewport is the display area of the viewport in which the window is perfectly mapped. Region Created according to Device Coordinates. It is the region in computer graphics which is a polygon viewing region. A viewport is defined by the GPORT command.

So, to display the image on the computer screen, we must map our window port to the viewport. The capture ratio of the window might not always be similar to or easily adjustable to the viewport. Thus, some necessary transformations ad adjustments like clipping and cropping are performed on the window.